\Col*lo"di*on\, n. [Gr. ? like glue; ko`lla glue + ? form. Cf. {Colloid}.] (Chem.) A solution of pyroxylin (soluble gun cotton) in ether containing a varying proportion of alcohol. It is strongly adhesive, and is used by surgeons as a coating for wounds; but its chief application is as a vehicle for the sensitive film in photography. {Collodion process} (Photog.), a process in which a film of sensitized collodion is used in preparing the plate for taking a picture. {Styptic collodion}, collodion containing an astringent, as tannin.